HTTP Header Parser

What is HTTP Header Parser?

HTTP Header Parser analyzes raw HTTP request and response headers, identifying each header's purpose, RFC reference, security implications, and common misconfiguration issues. It parses both request headers (Accept, Authorization, Content-Type, User-Agent) and response headers (Cache-Control, Content-Security-Policy, Strict-Transport-Security, X-Frame-Options), highlighting security-relevant headers that are missing or misconfigured. The tool also decodes encoded header values like Base64 Authorization tokens and parses complex headers like Cache-Control directives.

Backend developers debugging HTTP requests, security engineers auditing response headers, and DevOps engineers configuring web server and CDN settings. The tool runs entirely in your browser — your data never leaves your device.

How to Use HTTP Header Parser

1. Paste raw HTTP headers copied from browser DevTools, curl output, or server logs
2. View each header with its explanation, RFC reference, and any detected issues
3. Check the security audit panel for missing headers like HSTS, CSP, and X-Content-Type-Options
4. Click on complex headers like Cache-Control or CSP to see each directive parsed individually

Common Use Cases

• Debugging API requests by examining exactly which headers are being sent and received
• Auditing security headers on web responses for OWASP compliance
• Understanding caching behavior by parsing Cache-Control, ETag, and Expires headers
• Analyzing Content-Security-Policy headers to identify why resources are being blocked

Pro Tips

• The six essential security response headers are: Strict-Transport-Security, Content-Security-Policy, X-Content-Type-Options, X-Frame-Options (or CSP frame-ancestors), Referrer-Policy, and Permissions-Policy — missing any of these is flagged as a security gap
• Cache-Control: no-cache does NOT mean 'don't cache' — it means 'revalidate before using the cached copy'; use no-store to actually prevent caching entirely
• The Server header (e.g., 'Apache/2.4.41 (Ubuntu)') leaks your web server version — attackers use this for targeted exploit scanning; suppress or genericize it in production

Why Use This Tool?

• Privacy-first: All processing happens locally in your browser. No data is transmitted to any server.
• No installation required: Works in any modern browser on desktop or mobile.
• Completely free: No account, no credit card, no usage caps.
• Fast and reliable: Powered by modern Web APIs for near-instant results.

Related Concepts

Learn more about related topics: RFC 7230, Security headers, Content-Security-Policy, HSTS.

Frequently Asked Questions